We studied the calling behavior of three Italian populations of the green toad (Bufo viridis). An analysis of male advertisement calls revealed a significant influence of both body size and temperature on call properties. Large males uttered relatively low-pitched and long calls. Temperature affected temporal but not spectral parameters. Therefore, female phonotaxis experiments were focused on calls differing in fundamental frequency, which was the most constant parameter within males and a potentially reliable acoustic indicator of male size. In discrimination experiments, females preferred low-pitched calls. A skeletochronological analysis showed a significant relationship between early sexual maturity and large size, which may be an indicator of potential mate quality in anurans.